Patent Document 1 below describes a vehicle side-on collision airbag device in which an airbag main body is formed from left and right side main base cloths, and a side face base cloth that couples together outer peripheral edges of the main base cloths. A discharge hole (vent hole portion) that discharges gas from inside the airbag main body is formed at a front central portion of the side face main cloth.
Patent Document 2 below describes a side airbag formed by stitching together peripheral edge portions of two side panels. An air passage hole (vent hole portion) is formed by interrupting a portion of this stitching.    Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. H08-225054    Patent Document 2: JP-A No. 2010-535121